Gasification system

ABSTRACT

A coal gasification system includes a coal gasifier that allows, for example, coal, as carbonaceous solid fuel, to react in the furnace with a gasifying agent (for example, air or oxygen) to generate combustible gas from the coal, a pulverized coal supply device (solid fuel supply means) that pulverizes the coal into a fine powder form and charges the coal into the coal gasifier, and an ash supply device (ash supply means) that charges ash of the coal (pulverized coal) to an inside of the coal gasifier. The ash supply device is configured to recharge slag that is generated when the pulverized coal is gasified in the coal gasifier and is discharged, into the coal gasifier as the ash. The slag is melted in a combustor to be molten slag, and adheres to an inner wall of the combustor to function as a refractory material.

TECHNICAL FIELD

The present invention relates to a gasification system that gasifies carbonaceous solid fuel to generate combustible gas fuel, and particularly relates to a gasification system that can enhance heat resistance of a combustor.

BACKGROUND ART

There are gasification systems that gasify carbonaceous solid fuel such as coal to generate combustible gas fuel, as disclosed in PTL 1 and PTL 2, and the like. As a gasifier that performs gasification in such a gasification system, various methods such as a fixed bed method, a fluidized bed method, and an entrained bed method are proposed. In these methods, an entrained bed method pulverizes solid fuel into fine powder, supplies the pulverized solid fuel into a furnace with a temperature of a melting point of the fuel ash or higher (about 1300 to 1800° C.) with a gasifying agent such as oxygen and air to cause the pulverized solid fuel to react, and converts combustible components in the fuel into gas and converts ash into slag. Therefore, the entrained bed method has the features of having higher gasification efficiency, having a larger number of applicable coals, being more excellent in environmental suitability and the like, and is suitable for manufacturing fuel and raw materials of synthetic gas, combined power generation, fuel cell and the like, and therefore, the method is being developed domestically and overseas.

When carbonaceous solid fuel is gasified in a gasifier of an entrained bed method as above or the like, the temperature of a combustor (a furnace) reaches a maximum temperature as high as approximately 1800° C. The temperature is close to the heat resistance limit of the refractory material that forms the inner wall surface of the combustor. Accordingly, since there is anxiety about durability of the combustor if the combustor is left as it is, the molten slag that is generated by ash melting at the time of gasification of carbonaceous solid fuel is caused to adhere to the inner wall surface of the combustor, and the molten slag itself is used as the heat resisting material for the combustor. In other words, the heat resistance of the combustor is designed with the state in which the molten slag adheres to the inner wall surface of the combustor as a reference.

Incidentally, both the gasifiers disclosed in PTL 1 and PTL 2 separate ash from the generated gas, capture the ash, recharge the ash into the gasifiers again, and thereby burn the unburnt components again, in order to remove the unburnt carbon components contained in the ash (char, fly ash) that is released with the gas generated from carbonaceous solid fuel.

Meanwhile, the slag that is generated in the gasifiers (the matter obtained by the ash of coal ash being melted in the high-temperature gasifiers, flowing down into water at the lower portions of the gasifiers and being rapidly cooled to be solidified into a glass form, and being discharged in a grain form) is discharged directly to the outsides and properly treated in both cases.

CITATION LIST Patent Literature

-   {PTL 1} Japanese Unexamined Patent Application, Publication No. Sho     62-125891 -   {PTL 2} Description of United States Patent No. 000001325H

SUMMARY OF INVENTION Technical Problem

As described above, the heat resistance of the combustor of a gasifier is designed with the state in which molten slag adheres to the inner wall surface of the combustor as a reference. Therefore, if carbonaceous solid fuel with less ash is supplied, the amount of the molten slag adhering to the inner wall surface of the combustor becomes insufficient, and there is the fear of reduction of the heat resistance of the combustor. Accordingly, in the conventional gasification system (gasifier), gasification of the carbonaceous solid fuel with less ash is difficult, and the kind of applicable carbonaceous solid fuel is limited.

In order to enable gasification of carbonaceous solid fuel with less ash, cooling performance of the combustor has to be enhanced, and a complicated cooling structure needs to be adopted. Therefore, there arises the problem that new construction of a gasifier and alteration of an existing gasifier become difficult. Furthermore, adoption of a cooling structure brings about the disadvantage of reduction of the thermal efficiency of the entire gasification system.

The present invention is made in the light of the above described problems, and has an object to provide a gasification system capable of increasing the number of kinds of applicable carbonaceous solid fuel by enabling stable gasification of carbonaceous solid fuel with less ash, by a simple configuration that is also applicable to an existing gasifier.

Solution to Problem

In order to solve the above described problems, the present invention adopts the following solutions.

Namely, a first aspect of a gasification system according to the present invention includes a gasifier that allows carbonaceous solid fuel to react in the furnace with a gasifying agent to generate combustible gas from the carbonaceous solid fuel, a solid fuel supply means (a pulverized coal supply device) that pulverizes the carbonaceous solid fuel into a fine powder form and charges the carbonaceous solid fuel into the gasifier, and an ash supply means (an ash supply device) that charges ash of a carbonaceous raw material to an inside of the gasifier.

According to the first aspect, the carbonaceous solid fuel that is pulverized into a fine powder form is charged into the gasifier from the solid fuel supply means, and the ash of the carbonaceous raw material is charged into the gasifier from the ash supply means. The ash is charged into the gasifier when the carbonaceous solid fuel reacts with the gasifying agent in the gasifier, whereby the amount of molten slag that is generated as whole ash after reaction of the carbonaceous solid fuel increases. The increased molten slag adheres to an inner wall of a combustor of the gasifier that has a high temperature and functions as a heat resisting material for the combustor.

Therefore, even if the ash that the carbonaceous solid fuel originally has is less, the small amount of ash is supplemented by the ash that is charged from the ash supply means to increase a total ash amount, that is, the amount of the molten slag that is melted in an inside of the combustor and adheres to an inner wall surface of the combustor is increased, and heat resistance of the combustor can be enhanced. Accordingly, even with carbonaceous solid fuel with less ash, the carbonaceous solid fuel can be stably gasified, whereby the number of kinds of applicable carbonaceous solid fuel can be increased.

Further, in a second aspect of the gasification system according to the present invention, the ash supply means in the first aspect may be configured to recharge ash that is generated when the carbonaceous solid fuel is gasified in the gasifier and is discharged, into the gasifier, as the ash.

According to the second aspect, the ash of the carbonaceous solid fuel generated in the gasifier is charged into the gasifier again after the ash is temporarily discharged from the gasifier, and therefore, the same ash as the ash of the carbonaceous solid fuel that reacts in an inside of the gasifier is recharged into the gasifier. Accordingly, it hardly occurs that the reaction conditions in the inside of the gasifier change by recharge of ash. Further, since a flow state of the molten slag that adheres to the inner wall surface of the combustor does not change, an operation in a predictable range is enabled, and stable gasification can be performed.

Further, in a third aspect of the gasification system according to the present invention, the ash supply means in the first aspect may be configured to charge ash that is generated in another combustion system into the gasifier as the ash.

Further, in a fourth aspect of the gasification system according to the present invention, the ash supply means in the first aspect may be configured to be able to charge both of ash that is generated when the carbonaceous solid fuel is gasified in the gasifier and is discharged, and ash that is generated in another combustion system, into the gasifier, as the ash.

According to the third and the fourth aspects, even when the molten slag is difficult to cause to adhere to the inner wall surface of the combustor at such a time as the time of start of operation of the gasifier, and at the time when the ash of the carbonaceous solid fuel is extremely less, the insufficiency of the molten slag can be supplemented by charging the ash that is generated in another combustion system into the gasifier. Accordingly, stable gasification can be continuously performed.

In the fourth aspect, the ash that is charged into the gasifier may be 2 to 50% in weight ratio with respect to a charge amount of the carbonaceous solid fuel.

By doing as above, the amount of the ash that is charged into the gasifier is made a proper amount to enhance heat resistance of the inner wall surface of the combustor to perform stable gasification, and the amount of the ash that is mixed into the generated combustible gas is decreased, whereby separation of the combustible gas and ash can be made easy.

Further, in a fifth aspect of the gasification system according to the present invention, the ash supply means in any one of the first to the fourth aspects may be configured to pulverize the ash into a fine powder form and recharge the ash to the inside of the gasifier together with the carbonaceous solid fuel.

According to the above described fifth aspect, as the charge section that charges the ash into the gasifier, the charge section for carbonaceous solid fuel that is originally included in the gasifier is made sharable. Therefore, ash is enabled to be charged into the gasifier to increase the amount of the molten slag, and the heat resistance of the combustor can be enhanced, without any alterations added to the existing gasifier.

Further, in the combustor, the charge section for ash is not additionally opened, except for the charge section for carbonaceous solid fuel. Accordingly, air and gas for conveying ash do not flow into the combustor from here, and the disadvantage of reducing the internal temperature of the combustor does not arise. Therefore, the flow characteristic of the ash in the combustor does not change from the conventional one, whereby stable gasification is enabled.

Further, a sixth aspect of the gasification system according to the present invention may have a configuration in which the ash supply means operates by being controlled by a control unit, and the control unit controls the ash supply means so that an amount of the ash that is generated from the gasifier becomes a target ash generation amount with a predetermined ratio with respect to a charge amount of the carbonaceous solid fuel, and discards ash that is generated in excess of the target ash generation amount without charging the ash into the gasifier.

According to the sixth aspect, the amount of the ash that is generated from the gasifier always has a value close to the target ash generation amount. Thereby, ash is made an optimum amount of molten slag to be caused to adhere to the inner wall of the combustor, the heat resistance of the inner wall surface of the combustor is enhanced, and stable gasification can be performed. Further, the amount of the ash that is charged into the gasifier is suppressed to a minimum necessary amount, a large amount of ash is prevented from mixing into the generated combustible gas, and separation of the combustible gas and the ash can be made easy.

Further, in a seventh aspect of the gasification system according to the present invention, the target ash generation amount in the sixth aspect may be about 2 to 10% in weight ratio with respect to a charge amount of the carbonaceous solid fuel.

According to the seventh aspect, the amount of the ash that is recharged into the gasifier is made an optimum amount, the heat resistance of the inner wall surface of the combustor is enhanced, and stable gasification is performed. Further, the amount of the ash that mixes into the generated combustible gas is decreased, and separation of the combustible gas and the ash can be made easy.

Further, in an eighth aspect of the gasification system according to the present invention, the ash in any one of the first to the seventh aspects may be slag obtained after the carbonaceous solid fuel reacts in the gasifier.

As above, if as the ash to be charged into the gasifier with carbonaceous solid fuel, the slag obtained after the carbonaceous solid fuel reacts is adopted, the unburnt component contained in the slag is very small, and therefore, the ash that is recharged into the gasifier does not cause reaction again. Therefore, the reaction state of the carbonaceous solid fuel is stabilized, and the carbonaceous solid fuel can be favorably gasified. Further, the slag is in a glass form and is favorable in crushability, and therefore, is easily to handle.

Advantageous Effects of Invention

As above, according to the gasification system according to the present invention, by the simple configuration that is also applicable to the existing gasifier, stable gasification of carbonaceous solid fuel with less ash is enabled, and the number of kinds of applicable carbonaceous solid fuel can be increased.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a schematic configuration of a coal gasification system according to an embodiment of the present invention.

FIG. 2 is a graph showing a change of a generation amount of slag to a charge amount of pulverized coal in a weight ratio.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a coal gasification system 1 (a gasification system) according to one embodiment of the present invention. The coal gasification system 1 is attached to, for example, an IGCC (Integrated coal Gasification Combined Cycle) plant, and includes a coal gasifier 2 (a gasifier). The coal gasifier 2 has a known structure in which a combustor 4 is housed in an inside of a main body pressure vessel 3, and allows carbonaceous solid fuel such as coal to react in the furnace with a gasifying agent such as air or oxygen to generate combustible gas from the carbonaceous solid fuel.

To the coal gasifier 2, an air supply device 12 is connected via an air supply line 11. The air supply device 12 is, for example, an air compressor, and pressurizes air or oxygen to supply it to the coal gasifier 2 as a gasifying agent.

Further, a pulverized coal supply device 15 (a solid fuel supply means) is connected to the coal gasifier 2 via a pulverized coal supply line 16. The pulverized coal supply device 15 pulverizes carbonaceous solid fuel such as coal into a fine powder form with a mill or the like not illustrated, and charges the fuel into the coal gasifier 2 via the pulverized coal supply line 16.

Furthermore, an ash supply device 20 (an ash supply means) is connected to the pulverized coal supply line 16 via an ash supply line 21. The ash supply device 20 is configured to pulverize solid slag that is generated when pulverized coal reacts to be gasified in the coal gasifier 2 and is discharged into a fine powder form with a mill or the like not illustrated as will be described later, and to recharge a predetermined amount of pulverized slag into the coal gasifier 2 via the pulverized coal supply line 16.

A slag recovery hopper 24 is installed in a bottom portion of the coal gasifier 2, and solid slag that is recovered into the slag recovery hopper 24 is fed to the ash supply device 20 via a slag supply line 25. Further, from another combustion system 28 such as a coal-fired boiler, ash such as slag and fly ash that do not contain an unburnt component is fed to the ash supply device 20 via an ash supply line 29. Namely, the ash supply device 20 is configured to be capable of charging any one of or both of the ash such as slag that is generated when the pulverized coal is gasified in the coal gasifier 2 and is discharged, and the ash that is generated in the other combustion system 28 into the coal gasifier 2.

The pulverized coal supply device 15 and the ash supply device 20 are both connected to the pulverized coal supply line 16, and therefore, the pulverized coal that is supplied from the pulverized coal supply device 15 and the ash (pulverized slag) that is supplied from the ash supply device 20 are mixed in an inside of the pulverized coal supply line 16 to be supplied together to the coal gasifier 2.

Further, the ash supply device 20 operates by being controlled by a control unit 31. Data D1 of a pulverized coal supply amount, and data D2 of a slag generation amount are respectively inputted into the control unit 31 from, for example, a pulverized coal supply amount sensor 32 provided at the pulverized coal supply line 16 and a slag generation amount sensor 33 that is provided at the slag recovery hopper 24. Further, various kinds of operation data D3 such as a combustion temperature, and a slag amount in the inside of the coal gasifier 2 are inputted into the control unit 31 from an operation monitor sensor 34 that is provided at the coal gasifier 2. On the basis of these respective data D1, D2 and D3, the control unit 31 controls the ash supply device 20, and controls the ash supply device 20 so that an amount of slag that is generated in the coal gasifier 2 becomes a target slag generation amount (a target ash generation amount) with a predetermined ratio to a total charge amount of the pulverized coal.

Meanwhile, a gas delivery line 38 for delivering generated gas is extended from a top portion of the coal gasifier 2, and the gas delivery line 38 is connected to a cyclone 39 that is a centrifugal separator. The cyclone 39 separates char that is an unburnt component of pulverized coal and is contained in generated gas. Further, a dust collector 42, a desulfurizer 43 and the like are connected to a generated gas conveying line 41 that is extended from the cyclone 39, and the generated gas conveying line 41 is finally connected to, for example, a gas turbine device 44.

Further, an air supply device 47 different from the aforementioned air supply device 12 is connected to the coal gasifier 2 via an air supply line 48. A char conveying line 51 that is extended from the cyclone 39 is connected to the air supply line 48, and a char recovery device 52 is connected to a midpoint of the char conveying line 51.

In the coal gasification system 1 configured as above, the pulverized coal that is supplied from the pulverized coal supply device 15 is charged into the coal gasifier 2 together with compressed air or the like via the pulverized coal supply line 16, is ignited by a burner not illustrated in the combustor 4, and causes reaction under a high pressure environment, and combustible components thereof become combustible gas, whereas the remaining ash becomes slag. The combustible gas that is generated here is delivered to an outside of the coal gasifier 2 from the gas delivery line 38, and is fed to the cyclone 39, where char and the like that are unburnt components of the pulverized coal are separated therefrom. Thereafter, the combustible gas passes the generated gas conveying line 41, has dust collected in the dust collector 42, and is subjected to desulfurization in the desulfurizer 43, after which, the combustible gas is supplied to the gas turbine device 44 to be combusted.

The char that is separated from the combustible gas in the cyclone 39 is temporarily recovered by the char recovery device 52 via the char conveying line 51, after which, the char is charged into the coal gasifier 2 via the air supply line 48 together with the gasifying agent (air, oxygen or the like) that is compressed by the air supply device 47, and is combusted in the combustor 4 with the pulverized coal.

The slag that is ash of the pulverized coal that causes reaction and generates the combustible gas in the inside of the combustor 4 of the coal gasifier 2 is melted by a high temperature in the inside of the combustor 4 and becomes a molten slag S. The molten slag S adheres to the inner wall surface of the combustor 4 and functions as a heat resisting material for the combustor 4, after which, the molten slag S flows down to a lower side, for example, is charged into water to be abruptly cooled, and becomes solid slag in a glass form. The solid slag is temporarily recovered in the slag recovery hopper 24, and thereafter is fed to the ash supply device 20 via the slag supply line 25.

The ash supply device 20 pulverizes the solid slag into pulverized slag. The pulverized slag is supplied to the pulverized coal supply line 16 via the ash supply line 21, is mixed into the pulverized coal in the inside of the pulverized coal supply line 16, and thereafter is supplied to the coal gasifier 2. At the same time, the compressed air generated in the air supply device 12 is supplied into the coal gasifier 2 as the gasifying agent via the air supply line 11.

The control unit 31 controls the ash supply device 20 on the basis of the data D1 of the pulverized coal supply amount that is inputted from the pulverized coal supply amount sensor 32 provided at the pulverized coal supply line 16, the data D2 of the slag generation amount that is inputted from the slag generation amount sensor 33 provided at the slag recovery hopper 24, and the various kinds of operation data D3 of the coal gasifier 2 that are inputted from the operation monitor sensor 34, and controls the ash supply device 20 so that the slag generation amount becomes the target slag generation amount with the predetermined ratio to the total charge amount of the pulverized coal. The control unit 31 performs control so that the slag that is generated in excess of the target slag generation amount is discarded without being charged into the coal gasifier 2. The above described target slag generation amount is set at about 2 to 10% in a weight ratio, preferably at about 2 to 4%.

FIG. 2 is a graph showing a change of the generation amount of slag with respect to the charge amount of pulverized coal in weight ratio. As shown here, at a time of start of operation of the coal gasifier 2, the generation amount of the slag, namely, the weight ratio of the slag that is discharged from the coal gasifier 2 with respect to the total amount of the pulverized coal that is charged is zero % as a matter of course. Subsequently, as the operation time increases more, the generation amount of the slag increases more. The control unit 31 controls the ash supply device 20 to charge more slag into the coal gasifier 2 until a time t1 when the generation amount of the slag reaches a target slag generation amount A (for example, a weight ratio of 3%), and controls the ash supply device 20 to charge slag to such an extent as to be able to keep it at t1 when the generation amount of the slag reaches the target slag generation amount A, and thereafter.

In particular, immediately after start of operation of the coal gasifier 2, a sufficient amount of solid slag is not generated from coal gasification, and therefore, the above described target slag generation amount A cannot be achieved. At such a time, ash such as slag and fly ash that are obtained from the other combustion system 28 is taken into the ash supply device 20 and is charged into the coal gasifier 2, by the control unit 31 or artificially.

As above, in the coal gasification system 1, the solid slag that is ash obtained after the pulverized coal reacts in the coal gasifier 2 is pulverized into a fine powder form and is recharged to the inside of the coal gasifier 2 by the ash supply device 20. Therefore, the pulverized slag is charged into the coal gasifier 2 when the pulverized coal reacts with the gasifying agent (air or oxygen) in the coal gasifier 2, whereby the amount of the molten slag S that is generated as total ash after reaction of the pulverized coal increases. The increased molten slag S adheres to the inner wall of the combustor 4 of the coal gasifier 2 that has a high temperature, and functions as the heat resisting material for the combustor 4.

Therefore, even if the content of the ash that is originally contained in the pulverized coal is low, the small amount of ash can be supplemented with the pulverized slag that is charged from the ash supply device 20, the total ash amount, namely, the amount of the molten slag S that is melted in the inside of the combustor 4 and adheres to the inner wall surface of the combustor 4 is increased, and the heat resistance of the combustor 4 can be enhanced. Accordingly, even with pulverized coal with less ash, or other kinds of carbonaceous solid fuel, this can be stably gasified, whereby the number of kinds of applicable carbonaceous solid fuel can be increased.

Further, the ash supply device 20 directly uses the slag that is generated when the pulverized coal supplied into the coal gasifier 2 is gasified, and is discharged, as the ash that is charged into the coal gasifier 2. Therefore, the same kind of slag as the slag of the pulverized coal that reacts in the inside of the coal gasifier 2 is recharged into the coal gasifier 2. Accordingly, it hardly happens that the reaction conditions in the inside of the coal gasifier 2 are changed by recharge of the slag.

Further, since the reaction conditions in the inside of the coal gasifier 2 are not changed as described above, the flow state of the molten slag S that adheres to the inner wall surface of the combustor 4 does not change. Therefore, an operation within a prediction range is enabled, and stable gasification can be performed. Furthermore, the slag after reacting in the coal gasifier 2 does not contain an unburnt component, and therefore, the slag that is recharged into the coal gasifier 2 does not cause reaction again. In this respect, the reaction state of the pulverized coal is stabilized, and the pulverized coal can be favorably gasified. Moreover, since the slag is solidified and has a property in a glass form with favorable crushability, the slag is easy to handle.

Furthermore, the ash supply device 20 is configured to be able to supply the ash generated in the other combustion system 28 as the ash that is charged into the coal gasifier 2, and is configured to be able to charge both the slag of the pulverized coal that is caused to react in the inside of the coal gasifier 2, and the ash that is generated in the other combustion system 28 into the coal gasifier 2. Therefore, even when the molten slag is difficult to cause to adhere to the inner wall surface of the combustor 4 at such a time as the time of start of operation of the coal gasifier 2, and the time when the ash of the pulverized coal and the other carbonaceous solid fuel is extremely less, insufficiency of the molten slag can be supplemented by charging the ash generated in the other combustion system 28 into the coal gasifier 2. Accordingly, stable gasification can be continuously performed.

The pulverized slag that is charged into the coal gasifier 2 from the ash supply device 20 is supplied to the pulverized coal supply line 16 from the ash supply line 21, is mixed with the pulverized coal that is supplied from the pulverized coal supply device 15 in the inside of the pulverized coal supply line 16, and is recharged into the coal gasifier 2 together with the pulverized coal. Therefore, as the charge section that charges ash into the coal gasifier 2, the charge section for pulverized coal (the pulverized coal supply line 16) that is conventionally included in the coal gasifier 2 can be made sharable. Therefore, charge of ash is enabled without any alterations added to the existing coal gasifier, or another kind of gasifier to increase the amount of the molten slag S, and heat resistance of the combustor 4 can be enhanced.

Moreover, in the inside of the combustor 4, a charge section for pulverized slag is not additionally opened, except for the pulverized coal supply line 16 to be the charge section for pulverized coal, and the air supply line 11 to be a supply section for compression air. Accordingly, from such an opening portion, air and gas for conveying the pulverized slag do not flow into the combustor 4, and the fear of reducing the internal temperature of the combustor 4 can be eliminated. Therefore, flow characteristics of the molten slag in the combustor 4 do not change from the conventional one, whereby stable gasification is enabled.

Further, the ash supply device 20 operates by being controlled by the control unit 31. The control unit 31, as shown in FIG. 2, controls the ash supply device 20 so that the amount of the slag that is generated from the coal gasifier 2 becomes the target slag generation amount A with the predetermined ratio with respect to the total charge amount of the pulverized coal, and controls the ash supply device 20 to discard the slag that is generated in excess of the target slag generation amount A without charging the slag into the coal gasifier 2. Therefore, the amount of the slag that is generated from the coal gasifier 2 always becomes a value close to the target slag generation amount A. Thereby, the optimum amount of the molten slag S is always caused to adhere to the inner wall of the combustor 4, the heat resistance of the inner wall surface of the combustor 4 is enhanced, and stable gasification can be performed. Furthermore, the amount of the slag that is charged into the coal gasifier 2 is suppressed to the minimum necessary amount, a large amount of ash is prevented from mixing into the generated combustible gas, and separation of the combustible gas and the ash can be made easy.

Note that the present invention is not limited to only the configuration of the above described embodiment, and modifications and alterations can be added within the range without departing from the scope of the present invention, and embodiments with modifications and alterations added like this are also included in the range of the right of the present invention.

For example, while the above described embodiment is configured to recharge slag into the coal gasifier 2, the present invention may be applied to the gasifier that gasifies other kinds of carbonaceous solid fuel, for example, petroleum coke and biomass fuel.

REFERENCE SIGNS LIST

-   1 COAL GASIFICATION SYSTEM (GASIFICATION SYSTEM) -   2 COAL GASIFIER (GASIFIER) -   4 COMBUSTOR -   11 AIR SUPPLY LINE -   12 AIR SUPPLY DEVICE -   15 PULVERIZED COAL SUPPLY DEVICE (SOLID FUEL SUPPLY MEANS) -   20 ASH SUPPLY DEVICE (ASH SUPPLY MEANS) -   24 SLAG RECOVERY HOPPER -   24 ANOTHER COMBUSTION SYSTEM -   28 CONTROL UNIT -   31 GAS DELIVERY LINE -   38 GAS TURBINE DEVICE -   A TARGET SLAG GENERATION AMOUNT (TARGET ASH GENERATION AMOUNT) -   S MOLTEN SLAG 

1-9. (canceled)
 10. A gasification system, comprising: a gasifier that allows carbonaceous solid fuel to react in the furnace with a gasifying agent to generate combustible gas from the carbonaceous solid fuel; a solid fuel supply means that pulverizes the carbonaceous solid fuel into a fine powder form and charges the carbonaceous solid fuel into the gasifier; an ash supply means that charges ash of a carbonaceous raw material to an inside of the gasifier; and a control unit that controls the ash supply means, wherein, in order to ensure heat resistance of the gasifier, the control unit controls the ash supply means so that an amount of the ash that is generated from the coal gasifier becomes a target ash generation amount with a predetermined ratio with respect to a total charge amount of the carbonaceous solid fuel.
 11. The gasification system according to claim 10, wherein the ash supply means is configured to recharge ash that is generated when the carbonaceous solid fuel is gasified in the gasifier and is discharged, into the gasifier, as the ash.
 12. The gasification system according to claim 10, wherein the ash supply means is configured to charge ash that is generated in another combustion system into the gasifier, as the ash.
 13. The gasification system according to claim 10, wherein the ash supply means is configured to be able to charge both of ash that is generated when the carbonaceous solid fuel is gasified in the gasifier and is discharged, and ash that is generated in another combustion system, into the gasifier, as the ash.
 14. The gasification system according to claim 13, wherein the ash that is charged into the gasifier is 2 to 50% in weight ratio with respect to a charge amount of the carbonaceous solid fuel.
 15. The gasification system according to claim 10, wherein the ash supply means is configured to pulverize the ash into a fine powder form and recharge the ash to the inside of the gasifier together with the carbonaceous solid fuel.
 16. The gasification system according to claim 10, wherein the target ash generation amount is about 2 to 10% in weight ratio with respect to a charge amount of the carbonaceous solid fuel.
 17. The gasification system according to claim 10, wherein the ash is slag obtained after the carbonaceous solid fuel reacts in the gasifier. 